The fly fishing industry continues to seek an improved balance of properties in fly fishing lines. Durability with low recoil memory on the one hand and shootability on the other has been difficult to balance. Durability with low recoil memory is generally associated with line flexibility while shootability is generally associated with less flexible or more rigid lines. Lack of durability, associated with brittleness or hardness of the flyline, can result in cracking under the normal stresses encountered in casting a flyline. Shootability, on the other hand, is enhanced by a hard or stiff line. Shootability refers to the line “shooting” through the fly rod guides with less resistance (through reduced friction) than a more flexible line might encounter, with consequent increase in casting distance. Recoil memory refers to the tendency of a flyline to remain coiled in the position it assumes when disposed on the fly reel. Memory is generally considered to be directly related to the stiffness of the line.
Various constructions for fly fishing lines are known in the art. U.S. Pat. No. 3,043,045, issued Jul. 10, 1962 to Martuch describes a fly fishing line comprising a nylon base core treated with a uniform priming coating of an adhesive material. A coating composition comprised of polyvinyl chloride in plasticizers is superimposed over the priming or adhesive coating.
U.S. Pat. No. 4,048,744, issued Sep. 20, 1977 to Chandler describes a fly fishing line having a buoyant tip section formed near the tip of the line. The fishing line is described as comprising a core member made of nylon, polyethylene or silk filaments treated with a priming coating of adhesive material over which is superimposed a coating composition comprising a dispersion of finely divided polyvinyl chloride in plasticizer.
U.S. Pat. No. 5,207,732, issued May 4, 1993 to Stark describes a fly fishing line comprising a core with a coating adherently bonded to the core. The coating is described as comprising a polyvinyl chloride resin with an in situ formed polymer to provide stiffness to the line. The polymer is derived from at least one polymerizable monomer including a polyfunctional acrylic monomer. Inclusion of the acrylic polymer is said to improve the combination of properties of durability, shootability, and recoil memory.
U.S. Pat. No. 5,296,292, issued Mar. 22, 1994 to Butters describes an elongated cylindrical tensile article made of one or more strands of a monofilament core surrounded by porous polytetrafluoroethylene (PTFE) which may be optionally coated or die sized on the outer surface for smoothness and/or abrasion resistance. The described article is said to be particularly useful for fly-casting lines for fishing.
U.S. Pat. No. 5,437,900, issued on Aug. 1, 1995 to Kuzowski describes porous expanded PTFE having a microstructure of nodes interconnected by fibrils where the surface of the material is modified to have increased hydrophobicity. The modified surface with increased hydrophobicity is said to possibly improve the flotation characteristics of fly fishing lines with an outer surface of porous expanded PTFE.
U.S. Pat. No. 5,625,976, issued on May 6, 1997 to Goodale also describes fly fishing lines and methods for their manufacture. The described lines include a core line portion and a coating comprising a copolymer of olefin, preferably ethylene, and acrylic material. The described lines are said to have a specific gravity of less than 1.0 without the necessity of adding microspheres or blowing agents and are said to be plasticizer free.
U.S. Pat. No. 6,321,483, issued on Nov. 27, 2001 to Kauss, also describes fly fishing lines and methods for their manufacture. The described fly fishing line and method for the manufacture of the line includes a core and an outer coating disposed around the core. The coating comprises polyvinyl chloride polymer, polytetrafluoroethylene, and optionally polyacrylate derived from the polymerization of a polyfunctional polymerizable acrylate monomer. The method described in the Kauss patent comprises coating a core with a plastisol comprising a polyvinyl chloride resin, polytetrafluoroethylene, and optionally one or more monomers. The method includes exposing the plastisol to conditions providing formation of a polymer derived from the polyvinyl chloride resin and adding polytetrafluoroethylene throughout the polymer.
Commercially available flylines manufactured by Fly Fishing Technology Ltd. in the United Kingdom and advertised under the trade designation AlRFLO 7000 TS are said to include a “glass smooth polymer coating” which includes PTFE and liquid lubricants. The flylines are advertised as having a five year non-crack guarantee with “super floatability” due to the inclusion of PTFE into the outer coating of the line on all floating models. The outer coating of these lines is a urethane combined with the aforementioned PTFE.
The fly fishing industry has continued to experiment with flyline compositions in order to improve various properties such as shootability, durability, floatability and the like.